Daltons Law of Partial Pressure

The behavior observed when two or more non-reacting gases are placed in the same container is given by Dalton’s Law of partial pressures. Dalton’s Law states that the total pressure exerted by a mixture of non-reacting gases is equal to the sum of the partial pressures of the various gases present in the mixture.

The partial pressure is defined as the pressure the gas would exert if it was alone in the container.

p_total = p_A  + p_B  + p_C

This gas law provides a simple way of calculating the partial pressure of each component, given the composition of the mixture and the total pressure.

Mole Fraction, X_A = n_A/n

Mole Fraction, X_B = n_B/n

n = n_A + n_B

p_A = n_ART/V, p_B = n_BRT/V and p = nRT/V

p_A = X_Ap

p_B = X_Bp